basement bathroom vent/drain pipes

I have a home build in 2003, the builder roughed in a basement bathroom with 2 drains & 2 vent pipes. I see no place to install a vanity with drain & vent pipe. A neighbor said I can run 11/2â€ PVC horizontally (about 5 feet) and connect into the showers vent pipe use a Sanitary tee to run the vanity's drain into the showers vent pipe, is this correct? Secondly won't I need to vent the vanityâ€™s drain? I can only see 2 ways to do this both require a 90 degree turn since I have to run horizontally to get to the showers vent pipe (if I can do this) Working from the vanity;

Option1- use a T fitting, run one side over the sanitary tee in the showers vent pipe, and come out the other side use a 90 degrees elbow to turn it upward to connect to larger vent pipe running horizontally overhead. The other opening would be to be used to connect the vanityâ€™s p trap into.

Option 2. use a sanitary tees and come out the bottom turn 90 degrees and run horizontally 5 ft over to another sanitary tee in the showers vent pipe. I could run out the top of the sanitary tee by the vanity to run upward to the vent pipe overhead.

Can I get some guidance or help resolving this or an I just up the creek?

Hi Mike,I have a home build in 2003, the builder roughed in a basement bathroom with 2 drains & 2 vent pipes. I see no place to install a vanity with drain & vent pipe.
All vent pipes are connected to a drain. If the plumber gave you a good rough you should have a 4" pipe to pick up the toilet, a 2" pipe coming out of the slab to pick up a shower, (this 2" pipe could be in a 14" square hole tub dap out) and a 2" pipe in a wall to pick up the lavatory/vanity and to vent your bathroom group. This is a normal basement rough in. As a rule the tub/shower's wetvented by connecting it it to the lavatory drain.

"A neighbor said I can run 11/2â€ PVC horizontally (about 5 feet) and connect into the showers vent pipe use a Sanitary tee to run the vanity's drain into the showers vent pipe, is this correct? Secondly won't I need to vent the vanityâ€™s drain? "
If f the second vent pipe isn't to pick up a kavatory then what's its function?
Your neighbor was almost correct. You may run the lavatory trap over to the shower vent and tie in with a san tee. However if the run will be up to 5 feet you will have to increase the pipe size to 2" as 1 1/2" can only run 3 1/2' by code.If it were me, I'd tap into the shower vent with a wye and a 45 deg fitting fairly low to the ground. I believe sanitees are ok in a vertical app like that though (pro to confirm). Putting it low just makes the 'wet vent' section as short as poss."

You can not do this as you would be building a "S" trap. "S" traps are illegal in all US codes and also in Canada. Make your lavatory stub-out 18" above the floor to the center and give it 1/4" to the foot slope to the san tee.
Essentially, there will be 2 junctions off the shower vent: one for the sink drain, one for the sink vent. The sink drain line will have a split close to the drain for the sink vent.

Not quite so. There will be only one "junction" on the shower vent. The drain from the lavatory. Since the lavatory will be connecting to the showers dry vent a extra lavatory vent won't be needed.

It's gonna work like this Mike, Cut a sanitary tee into the shower vent 17" off the floor to the center of the branch. Run a 2" drain from the san tee over to a 2 X 1/2" elbo and stub out 1 1/2" to pick up the lav. It's as simple as that. Are you quite sure that the second vent isn't there to pick up t6he lavatory???
Good luck, Tom

The way I intended to describe does not create an s trap. Here's a crude drawing. Apologies. Had to whip it out w/ Powerpoint @ work. Those tees should be wyes or sani's. Again - this is the way I did it, and the way I passed inspec. Not to say it'll fly anywhere else.

I originally did not have a separate sink vent as Speedball1 suggests. But the inspector failed me. The problem is that the sink drain has to travel quite a distance to get to the shower vent in my b-room. That dist was too far to be able to use the shower vent as the sink vent. If the sink vent is too far fm its trap, there is a risk of self siphoning.

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Hi Pash,
Are we talking about your house which has a extra long run to a vent pipe or are we talking about the first askers house which has a 5' run to the vent?
You have built a "loop vent" which will work just dandy on your extra long run but on Mikes 5' run a 2" pipe falls within code. You show san tees in your drawing and unless local codes forbid sanitary tees they are acceptable in my Code Book. Am I missing something here? PS. Your drawing looks just fine to me. Regards, Tom

One thing I read repeated over and over here is that fixtures should be individually vented.

I think you meant that ALL fixtures having a trap are mandated by code to be vented. Mandating individual vents would outlaw wet vents and increase the cost as well as installing unnecessary vent lines.

"Also, make sure the vent travels vertically by enough feet before xitiioning to horiz to meet the shower vent. It has to be some feet above flood line of sink."

Code mandates the you must revent back into a vent at least 6" above the flood rim of the fixture whose vent you're reventing back to.
Cheers, Tom

Heres what I've got from the replies. Coming up from the shower vent pipe 18" insert Sanitary tee, run 2" pvc over to where vanity sink will be. I should vent the vanity back into the vent pipe which is easiest by turning 90 degrees from vanity drain and go straight up & then T into overhead vent 2 'pvc (also new run). I am still unsure the best way to go from horizontal pvc into vanity (1 1/4 stub out) and then turn up & run 2' into "T" overhead for vnaity venting:

Can I connect off the shower vent with a sanitary tee (18"), run 2" pvc to vanity, 90 degree elbow (20") into a wyse or another sanitary tee (?), stub out 1 1/4 for vanity and then run 2"pvc up to the overhead vent connecting via a T fitting?

"Heres what I've got from the replies. Coming up from the shower vent pipe 18" insert Sanitary tee, run 2" pvc over to where vanity sink will be." STOP right there! If the run from the san tee is 5 foot or under, as you have indicated, then no vent in required. Prashster was referring to his own set up that has a longer run then yours and would require venting. Good luck Mike, Tom

Yup. I'm referring to my own setup. I have heard mixed opinions about venting if the proximity to a shared vent is less than X feet. I defer to Speedball's experience, but I'd get a 2nd opinion. I'd send a msg to HJ. He's pretty strict.

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Who's HJ and why is he pretty strict? And just what is he so strict about?
Chapter 14, Table 1409.3 of The Stardard Plumbing Code, Titled "Distance of Trap to Vent" gives us this.

Size of Fixture Drain in Inches Distance Trap to Vent

1 1/4------------------------------------2ft.6 in
1 1/2------------------------------------3ft.6 in
2----------------------------------------5ft.0 in
3----------------------------------------6ft.0 in
4---------------------------------------10ft.0 in
Prash, It doesn't get much more direct then this. Now you can tell me about the "mixed opinions" you have heard about shared vents, (wet vents). And why are we talking about your system when the Asker, (Mike) is asking for information? Are you a asker or a plumbing expert?
regards, Tom